SITE INDEX OF SIAMESE ( cochinchinensis Pierre) IN PLANTATIONS OF

TAENGMOO PHUNCHAISRI1, CHONGRAK WACHRINRAT1*, PONTHEP MEUNPONG1, SUWAN TANGMITCHAROEN2 AND NAWAPHONG KUASAKUN1

1 Department of Silviculture Faculty of Forestry Kasetsart University, Bangkok 10900, Thailand 2 Forest Research and Development Bureau, Royal Forest Department, Bangkok 10900, Thailand *Corresponding author, e-mail: [email protected]

ABSTRACT

Currently, decreased productivity of Siamese rosewood (Dalbergia cochinchinensis Pierre) is a problem due to illegal logging and the guidelines to manage this prevention being may be insufficient. Forest plantations should be promoted to achieve sustainable wood production for this species. Site index (SI) is a measure that can be used to predict forest productivity to identify appropriate sites for planting Siamese rosewood. The objective of the current study was to predict the SI for Siamese rosewood in Thailand. A sample of 78 temporary plots at 26 sites in 16 provinces of Thailand was selected to construct a site index curve with a base age of 30 yr. The results showed that the mean age of Siamese rosewood was 28 yr (between 13 and 55 yr), the mean diameter at breast height (DBH) was 20.03 cm (between 7.99 and 33.80 cm), and the mean dominant height was 20.79 m (between 7.32 and 24.82 m). The -1 -1 2 SI equation was: SI = e(lnHdo-12.476(A -Ab )) with an R value of 0.406 at p < 0.0001 (chosen as 30 yr in the present study). The equation indicated that 14, 18, 22, 26, and 30 m trees belonged to site classes Ι, ΙΙ, ΙΙΙ, ΙV, and V, respectively. Although in natural forest, Siamese rosewood is distributed in dry evergreen and mixed deciduous forests, in the present study, several sites in areas under both in situ and ex situ conservation were in the good and very good site categories. Thus, both areas can be used to Siamese rosewood and increase its productivity. Keywords: Siamese rosewood, Site index, Temporary plot

INTRODUCTION

Siamese rosewood (Dalbergia cochinchinensis Pierre) is generally found in the dry evergreen and mixed deciduous forests (Veesommai & Kavduengtain 2004) at elevations between 100 and 775 m above sea level (Eiadthong & Tangmitcharoen 2015). This species is native to Thailand, , , and . Over the years, this species has been severely affected by illegal logging, due to the quality of its hardwood and high durability, leading to a gradual reduction in its numbers (Cadena 2014). It was under the “vulnerable” category and red listed as a threatened species by the International Union for Conservation of Nature (IUCN) (IUCN, 2008), leading to a high demand of its wood and high price (Forest Research and Development Bureau 2010). This has been the prime reason affecting the numbers of Siamese rosewood trees. According to a survey by the Royal Forest Department of Thailand (2015), the price of Siamese rosewood heartwood was USD 30,000/m3 on the black market. Such a high price provided sufficient motivation for illegal logging in both natural forest and plantations. In 2014, 1,823 m3of Siamese rosewood was seized by the Thai government. The lawsuits filed for illegal logging of Siamese rosewood have increased while productivity has decreased every year in Thailand (Department of National Parks, Wildlife and Plant Conservation 2015). A similar situation exists for other threatened species with similar hardwood characteristics, such as Gamble ex Prain and Pterocarpus macrocarpus Kurz (Internal Security Operations Command 2014). The diminishing number of individual trees of such species is of grave concern and needs to be dealt with urgently. Plantations can play an important role in the success of reviving these species. Several economically viable species, including Siamese rosewood, have been promoted in certain areas by the Thai government. Two distinct procedures have been applied: 1), in situ conservation areas (conservation of ecosystems and natural habitats and maintenance and recovery of the population that allows the species to exist in the natural environment and in the case of domesticated or cultivated plant species in an environment in which those species have developed special properties); and 2) ex situ conservation (conservation of plant genetic resources outside the natural habitat). The current methods being used for selecting areas where this planting Siamese rosewood need to be improved and implemented in the future. (Tangmitcharoen 2013) Site index (SI) is one of the measures used to predict forest productivity, wood volume, and the potential rate of growth (Hanson et al. 2002). The relationship between dominant height and age was used to construct a site index curve by Mayhew & Newton (1998). There are several techniques for determining SI such as: (1) the proportion curve or guide curve method; (2) the parameter prediction method; and (3) the different equation method (Clutter et al. 1983). In Thailand, the proportion curve method has been used for assessing and predicting the site quality of Tectona grandis L.f. (Forestry Research Center 1669) and Eucalyptus camaldulensis Dehnh. plantations in the lower northeastern parts (Insaun 2009) and Acacia mangium Willd. plantation in Trat province(Jumwong 2006). Siamese rosewood research has also focused on other dimensions such as inventory, ecology, growth and yield. The prediction of SI for Siamese rosewood is yet to be undertaken. Thus, the objective of the current research was to summarize the growth characteristics and develop a SI for Siamese rosewood found in plantations in Thailand.

MATERIALS AND METHODS

Study site and data collection Thailand is a tropical country located between 50 37" N and 20027" N latitude and 97o 22" E and 105o 37" E longitude. The annual rainfall ranges between 1,200 and 1600 mm and the mean annual rainfall is 1,587 mm. The mean annual temperature is around 270 C (Thai Meteorological Department 2014). The study was conducted in Siamese rosewood plantations owned by the Royal Forest Department of Thailand (RFD) and the Forest Industry Organization (FIO). Table 1 Summary of 26 Siamese Rosewood study sites in Thailand used in the study. No Plantation Province Region Code latitude longitude

1 Kam Phaeng Phet Silvicultural Research Station Kamphaengphet N KPP1 16๐ 33’ 99๐ 30’

2 Kam Phaeng Phet Silvicultural Research Station Kamphaengphet N KPP2 16๐ 34’ 99๐ 30’ 3 Kam Phaeng Phet Silvicultural Research Station Kamphaengphet N KPP3 16๐ 33’ 99๐ 30’ 4 Phit Sa Nu Lok Silvicultural Research Station Phitsanulok N PNL 16๐ 50’ 100๐ 53’ 5 In Tha Khin Silvicultural Research Station Chiangmai N ITK 19๐ 9’ 98๐ 56’ 6 Tha Tum Silvicultural Research Station Surin NE TT 15๐ 18’ 103๐ 45’ 7 Nong Khu Silvicultural Research Station Surin NE NK 14๐ 41’ 103๐ 45’ 8 Huai Tha Silvicultural Research Station Sisaket NE HT1 14๐ 52’ 104๐ 26’ 9 Huai Tha Silvicultural Research Station Sisaket NE HT2 14๐ 52’ 104๐ 26’ 10 Pha Nok Khao Silvicultural Research Station Khon Kaen NE PNK 16๐ 50’ 101๐ 56’ 11 Loei Forestry and Forest Products Research Center Loei NE LOEI 16๐ 52’ 101๐ 56’ 12 Udon Tha Ni Forest Nursery Center Udon Thani NE UD 16๐ 50’ 102๐ 56’ 13 Mu Si Silvicultural Research Station Nakhon Ratchasima NE MS1 14๐ 30’ 101๐ 25’ 14 Mu Si Silvicultural Research Station Nakhon Ratchasima NE MS2 14๐ 30’ 101๐ 25’ 15 Ka La Sin Silvicultural Research Station Kalasin NE KLS 16๐ 28’ 103๐ 24’ 16 Dong LanSilvicultural Research Station Khon Kaen NE DL 16๐ 49’ 101๐ 59’ 17 Huai Rang Plantation Trat E HR 12๐ 26’ 102๐ 33’ 18 Tha Kum Noboru Umeda Plantation Trat E TK1 12๐ 22’ 102๐ 40’ 19 Tha Kum Noboru Umeda Plantation Trat E TK2 12๐ 23’ 102๐ 39’ 20 Tha Kum Noboru Umeda Plantation Trat E TK3 12๐ 23’ 102๐ 39’ 21 Rat Cha Bu Ri Silvicultural Research Station Ratchaburi C RBR 13๐ 34’ 99๐ 44’ 22 Central Silvicultural Research center Kanchanaburi C PK1 14๐ 24’ 98๐ 55’ 23 Central Silvicultural Research center Kanchanaburi C PK2 14๐ 24’ 98๐ 55’ 24 Thong Pha Phum Silvicultural Research Station Kanchanaburi C TPP 14๐ 42’ 98๐ 39’ 25 Southern Silvicultural Research center Songkhla S PT 7๐ 1’ 100๐ 17’ 26 Sai Thong Silvicultural Research Station Prachuap Khiri Khan S ST 10๐ 59’ 99๐ 27’ Note: Regions as identified by the Thai Meteorological Department are: “N” is north, “NE” is northeast, “E” is east, “C” is central, and “S” is south. Twenty-six sites were selected from16 provinces distributed throughout Thailand (Table 1 and Figure 1). Three temporary sample plots were selected per site (78 temporary sample plots in total). Each temporary plot was 0.16 ha in size and the diameter at breast height over bark (DBH) at 1.30 m above ground and total height (H), of all trees in the plot, were measured. Meteorological data from the Thai Meteorological Department for the sample sites are shown in Table 2.

Table 2 Meteorological data for the study sites. Average temperature Average relative Rainfall No. Station name Study sites (๐C) humidity (%) (mm/yr) 1 Phitsanulok 28.1 74.2 1399 PNL 2 Kamphaengphet 28.5 76.8 1372 KPP1,KKP2,KKP3 3 Chiangmai 27.2 71.3 1158 ITK 4 Pakchong Agromet 26.4 73.3 1206 MS1,MS2 5 Thatom 27.9 74.1 1313 TT 6 Surin 27.7 72.4 1454 NK 7 Sisaket Agromet 27.7 74.8 1420 HT1,HT2 8 Loei 26.9 73.2 1310 Loei 9 Kalasin 27.2 72.0 1340 KLS 10 Khon Kaen 27.7 70.4 1196 PNK,DL 11 Udonthani 27.5 71.1 1338 UD 12 Trat 27.9 81.4 4988 HR,TK1,TK2,TK3 13 Ratchaburi 28.6 78.1 1067 RBR 14 Kanchanaburi 29.0 70.4 1104 PK1,PK2 15 Thong Phaphum 28.1 78.5 1827 TPP 16 Prachuap Khiri Khan 28.8 76.3 1056 ST 17 Hatyai 28.3 79.4 1793 PT

Determination of SI equation The height of the tree is important in the creation of the SI but the mean height of a stand is usually sensitive to age, site, class and stand density. Thus, the dominant height is normally used to represent a stand and specifically mean height of the 100 tallest trees/ha is most widely used to construct an SI (Alder 1980). In this case, the SI equation was constructed using the top 16 tallest trees per plot (plot size of 0.16 ha). There are several techniques for determining the SI. However, the current study only had access to data derived from temporary plots and consequently, the guide curve method was used (Alder1980) based on equation (1) and the SI equation was constructed using equation (2). -k ln(Hdo) = Inb0+b1A …………………………….……………………..………………...(1),

-1 -1 SI = e(ln(Hdo)+ b1 (A -Ab ))……………………….……………………………...……(2), where Hdo is the dominant height, ln is the natural logarithm, b0 and b1 are regression coefficients, A is the stand age, k = 1, SI is the site index, e is the natural exponent, and Ab is the base age (chosen as 30 yr in the present study). Based on equation 2, 5 site classes were used (I, II, III, IV, and V) indicating very poor, poor, moderate, good, and very good sites, respectively. The upper and lower bounds for each SI class were determined using simple interpolation and extrapolation in the Excel software package (Microsoft Corp.; Redmond, CA, USA).

. Figure 1. Location of Siamese rosewood study sites in Thailand.

RESULTS AND DISCUSSION

The growth characteristics of Siamese rosewood, as determined from 26 sites, are presented in Table 3. The mean age was 28 yr ( between 13 and 55 years), mean DBH was 20.03 cm (between 7.99 and 33.80 cm), mean H was

16.48 m (ranging between 6.18 and 23.20 m), and the mean Hdo was 20.79 m (ranging between 7.32 and 24.82 m). The mean DBH, H and Hdo of the TT plantation were lowest (see Table 1 for identification of the plantation abbreviations used). Both the highest mean DBH and mean H were in the KLS plantation and the highest mean of Hdo was in the PNL plantation. The stand mean dominant heights for KLS and PNL were similar (24.18 and 24.82 m, respectively) despite their stand ages being rather different (42 and 27 years, respectively). This could be interpreted as the younger stand age alone indicating site suitability which is not necessarily correct. Thus, the methodology for assessing the appropriate site using the site index had to decrease the bias associated with the different-aged stands. The SI equation for Siamese rosewood obtained using the proportional curve method at a base age of 30 yr was -1 -1 2 SI = e(lnHdo-12.476(A -Ab )) with an R value of 0.406 and p < 0.0001. Five stratification levels were used based on site classes I through V for H values of 14, 18, 22, 26, and 30 m, respectively. Figure 2 shows that a 30 year old Siamese rosewood tree with a dominant height of 22 m belonged to site class III. This stand was predicted as a moderate site for planting. Likewise, we also determined the best site planting (class V) for which trees had to be 30 m tall at age 30 yr. In contrast, trees on poorer sites (site I) were only 14 m tall at age 30 yr.

Table 3. Growth characteristics of Siamese rosewood in plantations located at 26 sites in Thailand. Age DBH ± SD H ± SD H ± SD No Site code do (yr) (cm) (m) (m) 1 TT 13 7.99 ± 3.94 6.18 ± 2.65 7.32 ± 2.22 2 RBR 22 23.42 ± 7.48 14.06 ± 3.30 14.55 ± 3.00 3 NK 25 13.23 ± 5.66 10.78 ± 3.85 16.03 ± 2.40 4 HT1 25 18.38 ± 6.06 14.58 ± 3.56 17.55 ± 1.49 5 HT2 25 21.02 ± 8.27 16.64 ± 4.13 17.43 ± 3.03 6 PNK 54 31.59 ± 7.16 22.64 ± 4.83 22.92 ± 4.70 7 LOEI 55 18.34 ± 6.07 17.42 ± 4.68 22.14 ± 2.43 8 UD 20 14.18 ± 5.73 13.82 ± 4.95 17.50 ± 4.13 9 KPP1 23 18.43 ± 7.30 16.72 ± 3.93 20.62 ± 1.90 10 MS1 28 21.15 ± 6.15 16.74 ± 3.18 20.02 ± 1.16 11 MS2 28 15.41 ± 6.29 13.96 ± 4.63 20.72 ± 2.38 12 HR 30 20.49 ± 7.92 16.21 ± 5.57 22.72 ± 2.61 13 TK1 32 25.06 ± 10.62 17.58 ± 6.16 23.53 ± 2.52 14 TK2 35 22.21 ± 8.48 15.82 ± 5.36 22.04 ± 1.74 15 TK3 36 25.40 ± 9.18 15.09 ± 5.25 21.38 ± 2.01 16 KLS 42 33.80 ± 9.92 23.20 ± 5.02 24.18 ± 4.94 17 PK2 18 18.39 ± 7.17 15.69 ± 4.64 20.71 ± 1.74 18 PK1 21 16.99 ± 7.65 15.09 ± 4.98 20.72 ± 1.53 19 KPP2 23 21.11 ± 7.07 19.47 ± 5.13 23.86 ± 2.38 20 KPP3 23 20.65 ± 9.55 17.54 ± 6.68 24.35 ± 1.96 21 PT 26 20.29 ± 8.14 18.24 ± 5.45 23.08 ± 0.90 22 PNL 27 15.97 ± 6.83 17.93 ± 5.45 24.82 ± 1.22 23 TPP 27 25.55 ± 11.14 20.01 ± 5.26 24.30 ± 1.28 24 ST 28 19.18 ± 7.67 19.64 ± 4.62 24.42 ± 1.15 25 DL 16 16.66 ± 5.68 16.06 ± 3.42 19.89 ± 1.92 26 ITK 20 15.85 ± 6.89 17.30 ± 5.16 23.60 ± 2.16

The number of study sites in the classifications were 1, 6, 9, 8, and 2 for SI classes I, II, III, IV, and V, respectively (Table 3). The lower and upper bounds of a very poor site class were 12.00 and 15.99 m, respectively, thus, the TT plantation was in this category. On the other hand, the lower and upper bounds of a very good site were 28.00 and 32.00m, respectively, and the DL and ITK plantations were in this category. In this study, most of the measured sites were in either the moderate or good site classes. Even though the growth rate based on DBH, H, and

Hdo of KLS and PNL were satisfactory, the results showed that DL and ITK were very good sites for Siamese rosewood compared at the base age of 30 years.

Figure 2. SI curves for Siamese rosewood in Thailand, where the dotted lines indicate the upper and lower bounds for each class based on simple interpolation/extrapolation.

Table 3 Site class, SI, and bounds at base age 30 yr of Siamese rosewood in Thailand, where the last column indicates the class according to site quality. Number of Upper limit Site class SI Lower limit (m) Site Code study sites (m) I (very poor) 14 1 12.00 15.99 TT II (poor) 18 6 16.00 19.99 RBR, NK, HT1, HT2, PNK, LOEI III (moderate) 22 9 20.00 23.99 UD, KPP1, MS1, MS2, HR, TK1, TK2, TK3, KLS IV (good) 26 8 24.00 27.99 PK2, PK1, KPP2, KPP3, PT, PNL, TPP, ST V (very good) 30 2 28.00 32.00 DL, ITK

Kliangpibool (2012) reported the suitable age for Siamese rosewood logs was between 18 and 25 yr at the price was USD 530 to 1,000/ha. However, the valuation of Siamese rosewood does not depend only on the quantity as the economic valuation of hardwood is important too. Kuasakun (2017) determined that the heartwood percentage of Siamese rosewood at the Mu Si Silvicultural Research Station (MS) was 68.30% while the SI for MS1 and MS2 were moderate site. In contrast, the heartwood percentage of Siamese rosewood at In Tha Kin Silvicultural Research Station (ITK) was 21.97 while the SI of ITK in the present study indicated it was a very good site; nevertheless, the increasing heartwood should result with increasing age as well (Visaratana, 2016)

Figure 3. In situ study sites of Siamese rosewood in northeastern and eastern Thailand

The natural distribution of Siamese rosewood is in the dry evergreen and mixed deciduous forests where located northeastern and eastern Thailand (Figure 3). Both regions have in situ conservation areas in which were located the study sites HR, TK1, TK2, and TK3 in the eastern, and TT, NK, HT1, HT2, PNK, LOEI, UD, MS1, MS2, KLS, and DL in the northeastern regions. Several sites in the in-situ conservation areas were not as appropriate as plantation sites as in the ex-situ conservation areas. The better ex situ sites were PK1, PK2, KPP1, KPP2, PT, PNL, TPP, ST, and ITK and were determined to be in the good and very good site classes (IV and V, see Figure 4). Suanpaga & Boonyuan (2016) compared the growth of eight appropriate tree species for planting in the Songkhla province, southern Thailand (an ex-situ conservation area for Siamese rosewood). Based on their results, they recommended Siamese rosewood and three other species (Dipterocarpus alatus Roxb, Xylia xylocarpa (Roxb.) Taub. var. kerrii (Craib & Hutch.) I. C. Nielsen, and Azadirachta excelsa (Jack) Jacobs).

Figure 4. Ex situ study site of Siamese rosewood in northern, central, and southern Thailand

Illegal logging has continued (Sudsakorn 2012) and so plans to increase sustainable productivity need to consider prevention and promotion. Chaipunya (2016) considered three aspects to maintain sustainable production from current stands: preventing illegal rosewood logging, preventing transportation, and preventing export of logs or wood products. In addition, Vissaratana et al. (2016) presented a case to promote both forest management and silvicultural techniques via plantations located on good sites to provide increasing productivity and economic value. Siamese rosewood can fix nitrogen through Rhizobium bacteria that can increase the health of ecological systems by fixing nutrients for use also by other species (Mungklarat 2001) and to improve soil fertility for reforestation purposes (So 2010). With regard to the current study, several sites in the ex-situ conservation area belonged to either the good or very good site classes. Thus, both ex-situ and in-situ conservation areas can be used for plantation purposes to increase productivity.

CONCLUSION A site index curve and equation are necessities for Thailand forestry to support Siamese rosewood plantations dating back more than 50 yr; however, extensive research commenced only recently. As a result, knowledge is still lacking of the site requirements for plantations of this species. Based on the growth characteristic of Siamese rosewood at 26 sites, five SI classes were constructed with most sites in the moderate site class. The SI equation developed in this study can be applied to help avoid planting of Siamese rosewood on inappropriate low quality sites and place more emphasis on identifying higher quality sites for plantation establishment. Several sites in the ex-situ conservation area belonged either to the good or very good site classes. Thus, both ex-situ and in-situ conservation areas can be used for plantation purposes to increase productivity.

ACKNOWLEDGEMENTS This research was supported in part by a Graduate Program Scholarship from the Graduate School, Kasetsart University, Bangkok, Thailand. We thank the Royal Forest Department of Thailand (RFD) and the Forest Industry Organization (FIO) for helping with the supply of data and assistance with fieldwork.

REFERENCES

Alder D. 1980. Forest Volume Estimation and Yield Prediction Vol. 2 yield production. Italy: Food and Agriculture Organization of United Nation. Cadena A. [Internet]. 2014. (Un) protected Areas: Rosewood Poaching in Thailand’s Dong Phayayen-Khao Yai World Heritage Site: IUCN.com; [updated 2014 FEB 24; cited 2018 JUN 20]. Available from:https://www.iucn.org/content/unprotected-areas-rosewood-poaching-thailand%E2%80%99s-dong- phayayen-khao-yai-world-heritage-site Chaipunya M. 2016. Monitoring of ad hoc plan's implementation on combating illegal logging of rosewood in Northeastern protected area 2013. Department of National Parks, Wildlife and Plant Conservation. Clutter JL, Fortson JC, Pienaar LV, Brister GH, Bailey RL. 1983. Timber Management, a Quantitative Approach, Wiley & Sons, New York, USA Department of National Parks, Wildlife and Plant Conservation. 2015. Special case to solve the problem in the area of Thap Lan National Park and Pang Sida National Park. Bangkok (Thailand): Department of National Parks, Wildlife and Plant Conservation Eiadthong W, Tangmitcharoen S. 2015. Ecologicaland Geographical Distributionsand Its Demographic Status of Siamese Rosewood (Dalbergia cochinchinensis Pierre) in Thailand In FORCONS proceeding 2015. Forestry Research Center. 1996. Exploration and yield assessment of the Forest Industry Organization. bangkok(Thailand): Faculty of Forestry, Kasetsart University. Forest Research and Development Bureau. 2010. General characteristics of Thai timbers. The Royal Forest Department of Thailand, Bangkok, Thailand. Hanson EJ, Azuma DL, Hiserote BA. 2002. Site index equations and mean annual increment equations for Pacific Northwest Research Station forest inventory and analysis inventories, 1985-2001. Res. Note PNW-RN-533. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 1-24 Insaun W, Wachrinrat C, Srigongpan R. 2009. Site quality assessment for Eucalyptus camaldulensis Dehnh. plantation in the lower part of Northeastern Thailand. Thai J. For.28: 13-27. Internal Security Operations Command. 2014. Model scheme of forest protection, Land invasion of the state and sustainable management of natural resources. Bangkok(Thailand): Internal Security Operations Command. International Union for Conservation of Nature [Internet]. 2008. IUCN Red list of threatened species. Version 2008. [cited 2018 JUN 20]. Available from http://www.iucnredlist .org/details/32625/0 Jumwong N. 2006. Site potential evaluation of Acacia mangium Willd. plantation area in Trat province, Thailand [Dissertation]. Retrieved from Kastsart University, Bangkok, Thailand. Kliangpibool N. 2012. Dalbergia Cochinchinensis pierre plantation. The Royal Forest Department of Thailand Kuasakun N. 2017. Growth and Heartwood Ratio of Siamese Rosewood (Dalbergia cochinchinensis Pierre) in Various Plantations. [Dissertation]. Retrieved from Kastsart University Mayhew JE, Newton AC. 1998. The Silviculture of Mahogany. England: CABI Publishing. Mungklarat J. 2001. The establishment of Dalbergia cochinchinensis Pierre plantation. . Bangkok(Thailand): Royal Forest Department of Thailand Royal Forest Department of Thailand. 2015. RFD news. Royal Forest Department of Thailand So, T; Theilade, I; Dell, B. 2010.Conservation and utilization of threatened hardwood species through reforestation - an example of xylocarpa (Kruz.) Craib and Dalbergia cochinchinensis Pierre in Cambodia. Pacific Conservation Biology 16: 101-116 Suanpaga w, Boonyuan S. 2016. Growth and Aboveground Biomass of Eight Tree Species in Species Trial for Appropriate Planting in Had Yai District, Songkhla Province. In FORCONS proceeding 2016. p.136 Sudsakorn C. 2012. Educational guidlines for preventing and combating an illegal logging of Pa Yung (Dalbergia cochinchinensis). [Dissertation]. Retrieved from Joint war College Tangmitcharoen S. 2013. Siamese Rosewood: Conservation and Management of Genetic Resources. In: Forestry Meeting on Production and Forest Research towards Sustainable Development, Royal Forest Department proceedings 2013. Thai Meteorological Department [Internet]. 2014. The climate of Thailand; [cited 2018 SEP 24]. Available from: https://www.tmd.go.th/info/climate_of_thailand-2524-2553.pdf Veesommai U, Kavduengtain P. 2004. Wild Trees in Thailand 1. Bangkok (TH). H.N.Group Co.,LTD. Visaratana T, Pinthong A, Hutasangchai C. 2016. Estimation heardwood of Dalbergia cochinchinensis Pierre in the Royal Forest Department.plantation: In FORCONS proceeding 2016. p.72